Hoyle Andrew, Bowers Roger G
Department of Computing Science and Mathematics, University of Stirling, Stirling FK9 4LA, UK.
Math Biosci. 2007 Nov;210(1):1-16. doi: 10.1016/j.mbs.2007.06.001. Epub 2007 Jun 10.
In this study we use the theory of adaptive dynamics firstly to explore the differences in evolutionary behaviour of a generalist predator (or more specifically an omnivorous or intraguild predator) in a predator-prey model, with a Holling Type II functional response, when two distinct forms for the carrying capacity are used. The first of these involves the carrying capacity as an emergent property, whilst in the second it appears explicitly in the dynamics. The resultant effect this has on the intraspecific competition in each case is compared. Taking an identical trade-off in each case, we find that only with an emergent carrying capacity is evolutionary branching possible. Our study then concentrates solely on the case where the carrying capacity appears explicitly. Using the same model as above, but choosing alternate trade-offs, we find branching can occur with an explicit carrying capacity. Our investigation finishes by taking a more general functional response in an attempt to derive a condition for when branching can or cannot occur. For a predator-prey model, branching cannot occur if the functional response can be separated into two components, one a function of the population densities, X and Z, and the other a function of the evolving parameter z (traded off against the intrinsic growth rate), i.e. if F(z,X,Z) = F(1)(z)F(2)(X,Z). This search for evolutionary branching is motivated by its possible role in speciation.
在本研究中，我们首先运用自适应动力学理论，探讨在具有Holling II型功能反应的捕食者 - 猎物模型中，当使用两种不同形式的环境容纳量时，泛化捕食者（或更具体地说是杂食性或集团内捕食者）进化行为的差异。其中第一种情况涉及环境容纳量作为一种涌现属性，而在第二种情况中它明确出现在动力学中。比较了这两种情况对种内竞争的最终影响。在每种情况下采用相同的权衡，我们发现只有当环境容纳量是涌现属性时才可能发生进化分支。然后我们的研究仅专注于环境容纳量明确出现的情况。使用与上述相同的模型，但选择不同的权衡，我们发现具有明确的环境容纳量时也会发生分支。我们的研究最后采用更一般的功能反应，试图推导分支发生或不发生的条件。对于捕食者 - 猎物模型，如果功能反应可以分离为两个分量，一个是种群密度X和Z的函数，另一个是进化参数z（与内在增长率进行权衡）的函数，即如果F(z,X,Z)=F(1)(z)F(2)(X,Z)，则不会发生分支。对进化分支的这种探索是由其在物种形成中可能扮演的角色所推动的。
